1. Field of the Invention
The present invention relates to a side structure for a vehicle body, which is capable of absorbing a collision energy exerted on the lateral side of the vehicle body, effectively.
2. Description of the Related Art
As the conventional side structure of this kind, Japanese Patent Publication (kokai) No. 9-169232 discloses one side structure where a reinforcement pipe is inserted into a lower frame element constituting a seat back frame for a passenger's seat.
However, the above side structure has been provided on the assumption of the vehicle's side collision with a general car having a relatively-low height, such as sedan. Therefore, if the vehicle has a side collision with another vehicle having a bumper arranged at a relatively-high position, for example, recent RV (recreational vehicle), truck, etc., there may be generated a moment which rotates the passenger's seat itself about one seat bearing point as a center since there is a great distance along a vehicle's height-direction between a load input point on the passenger's seat and the seat bearing point. Consequently, due to the rotation of the passenger's seat, a problem arises in that the impact load is not transmitted from the passenger's seat to a body framework, such as a floor panel, sufficiently. Under the situation, the seat back frame is required to have its axial strength necessary for the transmission of a load from the lateral side of the vehicle body and also an attachment strength resistant to the moment due to the load, causing the weight of the seat back frame to be increased disadvantageously.
Meanwhile, Japanese Patent Publication (kokai) No. 8-26144 discloses a structure which is directed to the countermeasure of the vehicle side collision beside a rear floor section of the vehicle body in order to improve the transmission of load on the vehicle framework. In this structure, a reinforcement member having a depression is secured to an automotive rear door. While, a cross member is mounted on an automotive rear floor. The cross member is provided, on a lateral side thereof, with a projecting stopper member for engagement with the reinforcement member. At the vehicle collision, the stopper member is fitted into the depression of the reinforcement member, so that the collision load is transmitted from the reinforcement member to the "closed-sectional" cross member while restricting an upward displacement of the rear door.
If the above-mentioned structure is applied to prevent the passenger's seat from rotating, then a problem arises in that the position of the passenger's seat cannot be adjusted freely. Nevertheless, if it is desired to maintain the degree of freedom in positioning the passenger's seat, then the cross member has to possess a number of stopper members corresponding to a number of seat positions, causing a problem of increasing the number of assembling steps remarkably.